Incorporation and activation of arsenic in single-crystal CdTe layers grown by metalorganic chemical vapor deposition

摘要

The electrical properties of arsenic doped CdTe epitaxial layers grown on GaAs (100) substrates by metalorganic chemical vapor deposition with dimethylcadmium and diethyltellurium are investigated. Tris(dimethylamino) arsine was used as the arsenic source. CdTe layers with arsenic concentration from 1.6.10(17) cm(-3) to 1.5.10(18) cm(-3) were obtained by varying only diethyltellurium/dimethylcadmium mole ratio from 6.2 to 0.5. The asgrown CdTe: As layers had p-type conductivity with hole concentration about 2.10(15) cm(-3) within diethyltellurium/ dimethylcadmium mole ratio 1-6.2 and n-type at diethyltellurium/dimethylcadmium = 0.5. Postgrowth annealing (250-500 degrees C) were used to increase the activation efficiency of arsenic. The highest hole concentration was 2.1.10(17) cm(-3) at arsenic concentration of 4.5.10(17) cm(-3), but the maximum activation efficiency approximately of 85% was achieved at lower concentration levels. The ionization energy of As-Te acceptor determined from temperature-dependent Hall measurements was in the range of 96-112 meV. Low-temperature photoluminescence emission spectra of arsenic doped CdTe layers showed a peak at similar to 1.51 eV which is associated with As-Te acceptor with ionization energy about 90 meV. Possible mechanisms of arsenic compensation in